@Jean-Francois *********
you are confusing TWO completely different things.
You hold a valid Non-O-A VISA (the sticker in your passport that you got from the thai consulate in your country).
HOWEVER
It's the tiny red entry stamp that lets you stay here. You are allowed to stay until Dec 3, 2021 on it
You have two options;
Exit re-enter the country on or before the date the VISA (sticker) expires (Nov 19 2021) and get a new year entry stamp (if you have covid and health insurance for another year
OR
Go to the immigration office and apply for a yearly extension of stay before the 3rd of Dec by showing you have 800K baht in the bank account for 2 months before you apply for the extension AND by having the 40k/400k mandatory health insurance by one of the 15 approved OA insurance carriers here in thailand.